Chemical mechanical polishing method

ABSTRACT

A planarization method includes: providing a substrate, wherein the substrate includes a first region and a second region having different degrees of hydrophobicity or hydrophilicity, the second region covering an upper surface of the first region; polishing the substrate with a polishing slurry until the upper surface of the first region is exposed; and continuing polishing and performing a surface treatment by the polishing slurry to adjust the degree of hydrophobicity or hydrophilicity of at least one of the first region and the second region. The polishing slurry and the upper surface of the second region have a first contact angle, and the polishing slurry and the upper surface of the first region have a second contact angle. The surface treatment keeps a contact angle difference between the first contact angle and the second contact angle being equal to or less than 30 degrees during the polishing.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.17/019,234, filed on Sep. 12, 2020, now allowed, which is a continuationof U.S. application Ser. No. 16/003,111, filed on Jun. 8, 2018, now U.S.patent Ser. No. 10/777,423 B2, which claims priority of U.S. provisionalapplication Ser. No. 62/590,068 filed on Nov. 22, 2017, all of whichdisclosures are incorporated by reference in their entirety.

BACKGROUND

Chemical mechanical polishing (CMP) is frequently used in integratedcircuit fabrications to reduce the thickness of a wafer or its overlyinglayer(s) and to planarize the surface of the wafer or its overlyinglayer(s). However, CMP suffers from material dishing. There is a need tomodify CMP in order to mitigate material dishing issue.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isemphasized that, in accordance with the standard practice in theindustry, various features are not drawn to scale. In fact, thedimensions of the various features may be arbitrarily increased orreduced for clarity of discussion.

FIG. 1A, FIG. 1B and FIG. 1C are schematic cross-sectional viewsillustrating a chemical mechanical polishing (CMP) method in accordancewith some embodiments of the present disclosure.

FIG. 2 is a flowchart illustrating a method for planarizing a substratein accordance with various aspects of the present disclosure.

FIG. 3 is a flowchart illustrating a chemical mechanical polishing (CMP)method in accordance with various aspects of the present disclosure.

FIG. 4 , FIG. 5 and FIG. 6 are schematic diagrams of a planarizationmethod in accordance with various aspects of some embodiments of thepresent disclosure.

FIG. 7 , FIG. 7A and FIG. 8 are schematic diagrams of a planarizationmethod in accordance with various aspects of some embodiments of thepresent disclosure.

FIG. 9 , FIG. 9A and FIG. 10 are schematic diagrams of a planarizationmethod in accordance with various aspects of some embodiments of thepresent disclosure.

FIG. 11A, FIG. 11B, FIG. 11C and FIG. 11D are schematic cross-sectionalviews illustrating a CMP method in accordance with some embodiments ofthe present disclosure.

DETAILED DESCRIPTION OF THE DISCLOSURE

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

As used herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising”, or “includes” and/or “including” or “has” and/or“having” when used in this specification, specify the presence of statedfeatures, regions, integers, operations, elements, and/or components,but do not preclude the presence or addition of one or more otherfeatures, regions, integers, operations, elements, components, and/orgroups thereof.

Furthermore, spatially relative terms, such as “beneath,” “below,”“lower,” “above,” “upper,” “on” and the like, may be used herein forease of description to describe one element or feature's relationship toanother element(s) or feature(s) as illustrated in the figures. Thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. The apparatus may be otherwiseoriented (rotated 90 degrees or at other orientations) and the spatiallyrelative descriptors used herein may likewise be interpretedaccordingly.

As used herein, the terms such as “first” and “second” describe variouselements, components, regions, layers and/or sections, these elements,components, regions, layers and/or sections should not be limited bythese terms. These terms may be only used to distinguish one element,component, region, layer or section from another. The terms such as“first” and “second” when used herein do not imply a sequence or orderunless clearly indicated by the context.

As used herein, the term “substantially” refers to the complete ornearly complete extent or degree of an action, characteristic, property,state, structure, item, or result. For example, a surface that is“substantially” coplanar with another surface would mean that these twosurfaces are either completely located in the same plane or nearlycompletely located in the same plane. The exact allowable degree ofdeviation from absolute completeness may in some cases depend on thespecific context. However, generally speaking the nearness of completionwill be so as to have the same overall result as if absolute and totalcompletion is obtained.

As used herein, the term “polishing slurry” refers to include an aqueousmixture having a chemical composition that may enhance, reduce, orotherwise modify a substrate polishing rate. In some cases, thepolishing slurry may also include polishing abrasives, chemical reagentsand other additives.

As used herein, the term “contact angle” is defined as the angle formedby a drop of liquid in contact with the surface of the substrate. Thevalue of the contact angle indicates the degree of hydrophobicity orhydrophilicity of the substrate. In some cases, when the contact angleis equal to or greater than 90 degrees, the substrate is hydrophobic.When the contact angle is less than 90 degrees, the substrate ishydrophilic.

FIG. 1A, FIG. 1B and FIG. 1C are schematic cross-sectional viewsillustrating a chemical mechanical polishing (CMP) method in accordancewith some embodiments of the present disclosure. As shown in FIG. 1A, asemiconductor structure 10 is provided. In some embodiments, thesemiconductor structure 10 includes a substrate 100, a first material102 and a second material 104. The first material 102 and the secondmaterial 104 have different degrees of hydrophobicity or hydrophilicity.The first material 102 may be configured as dielectric layer, and thesecond material 104 may be configured as conductive vias. The secondmaterial 104 over the first material 102 may need to be removed to forma plurality of separated conductive vias, and the surface of the firstmaterial 102 and the second material 104 may need to be planarized forsuccessive operations. A polishing slurry 120 may be dispensed over thesemiconductor structure 10, and a CMP operation may be performed toremove the second material 104 over the first material 102. As shown inFIG. 1A, since the second material 104 has the same degree ofhydrophobicity or hydrophilicity, the abrasives of the polishing slurry120 may be uniformly distributed over the second material 104, and thepolishing rate is substantially uniform throughout the second material104 at the beginning of the CMP operation.

As shown in FIG. 1B, when the second material 104 over the firstmaterial 102 is polished by the CMP operation, a first region 110 and asecond region 111 formed from different materials will be formed. Thefirst region 110 and the second region 111 have different degrees ofhydrophobicity or hydrophilicity. In some embodiments, the first region110 is a hydrophobic region and the second region 111 is a hydrophilicregion. The hydrophobic first region 110 includes a hydrophobic surface110 a and the hydrophilic second region 111 includes a hydrophilicsurface 111 a. Due to the different degrees of hydrophobicity orhydrophilicity between the first region 110 and the second region 111,the polishing slurry 120 are tended to approach and concentrate on thehydrophilic surface 111 a than on the hydrophobic surface 110 a.

As shown in FIG. 1C, the polishing rate in the hydrophilic second region111 with more polishing slurry 120 is higher than the polishing rate inthe hydrophobic first region 110 with less polishing slurry 120, andtherefore the concentrated polishing slurry 120 may cause dishing in thehydrophilic region 111 during the CMP operation.

In some embodiment of the present disclosure, a planarization method isprovided to mitigate dishing of the substrate or the overlying layer(s)on the substrate. The method may include a surface treatment by adding apH adjuster, a surfactant or a corrosion inhibitor to the polishingslurry. In some embodiments, the pH adjuster may modify the polishingslurry 120 to an alkaline or an acidic condition, which may help totransform a material of the hydrophobic region into another hydrophilicmaterial. In some embodiments, the surfactant or the corrosion inhibitorare configured to selectively bonded to the surface of one of thehydrophobic region and the hydrophilic region to alter the degree ofhydrophobicity or hydrophilicity, and thus may render its degree ofhydrophilicity of the hydrophobic region similar to that of the surfaceof the other one of the hydrophobic region and the hydrophilic region.In some embodiments, the surfactant or the corrosion inhibitor tends tobond to one of the hydrophobic region and the hydrophilic region than tothe other one of the hydrophobic region and the hydrophilic region byionic bond, hydrogen bond or the like. Therefore, the polishing slurrywill be uniformly dispersed on the hydrophobic region and thehydrophilic region such that dishing can be mitigated.

In some embodiments of the present disclosure, a planarizing method isdisclosed. In some embodiments, a substrate is polished by a planarizingmethod 200. The method 200 includes a number of operations, and thedescription and illustration are not deemed as a limitation as thesequence of the operations.

FIG. 2 is a flowchart illustrating a method for planarizing a substratein accordance with various aspects of the present disclosure. The method200 begins with operation 210 in which a substrate is provided, whereina surface of the substrate includes a first region and a second regionhaving different degrees of hydrophobicity or hydrophilicity. The method200 continues with operation 220 in which a surface treatment isperformed to the first region to render the degree of hydrophobicity orhydrophilicity of the first region in proximity to the degree ofhydrophobicity or hydrophilicity of the second region. The method 200proceeds with operation 230 in which the surface of the substrate ispolished using a polishing slurry to planarize the surface of thesubstrate.

The method 200 is merely an example, and is not intended to limit thepresent disclosure beyond what is explicitly recited in the claims.Additional operations can be provided before, during, and after themethod 200, and some operations described can be replaced, eliminated,or moved around for additional embodiments of the method.

In some embodiments, the surface treatment is performed by transforminga material of the first region into another material having a degree ofhydrophobicity or hydrophilicity similar to a degree of hydrophobicityor hydrophilicity of a material of the second region. In someembodiments, the material of the first region is transformed intoanother material by adding a pH adjuster to the polishing slurry. The pHadjuster may help to modify the polishing slurry to an alkaline or anacidic condition, which may help to transform the original material ofthe first region into another material having the degree ofhydrophobicity or hydrophilicity similar to that of the material of thesecond region. Accordingly, the polishing rates in the first region andthe second region are similar, and dishing during CMP operation can bealleviated. In some embodiments, the pH adjuster includes maleic acid,sulfuric acid, nitric acid, potassium hydroxide, amine, sodiumhypochlorite, tetramethylammonium hydroxide (TMAH), ammonium, or acombination thereof, but the material of the pH adjuster is not limitedthereto.

In some embodiments, the surface treatment is performed by adding asurfactant to the polishing slurry. In some embodiments, the surfactantis liable to bond to the surface of the first region than to the surfaceof the second region by ionic bond, hydrogen bond or the like. In someembodiments, the surfactant includes a functional group having a degreeof hydrophobicity or hydrophilicity similar to a degree ofhydrophobicity or hydrophilicity of a material of the second region. Asthe surfactant bonds to the surface of the first region, the surface ofthe first region and the surface of the second region may have similardegree of hydrophobicity or hydrophilicity. Accordingly, the polishingrates in the first region and the second region are similar, and dishingduring CMP operation can be alleviated. In some embodiments, thesurfactant includes an anionic surfactant, a cationic surfactant, anamphoteric surfactant, a nonionic surfactant, or a combination thereof.

In some embodiments, the surface treatment is performed by adding acorrosion inhibitor to the polishing slurry. In some embodiments, thecorrosion inhibitor is liable to bond to the surface of the first regionthan to the surface of the second region by ionic bond, hydrogen bond orthe like. In some embodiments, the corrosion inhibitor has a degree ofhydrophobicity or hydrophilicity similar to a degree of hydrophobicityor hydrophilicity of a material of the second region. As the corrosioninhibitor bonds to the surface of the first region, the surface of thefirst region and the surface of the second region may have similardegree of hydrophobicity or hydrophilicity. Accordingly, the polishingrates in the first region and the second region are similar, and dishingduring CMP operation can be alleviated. In some embodiments, thecorrosion inhibitor includes a short carbon chain corrosion inhibitorwith a carbon number less than 20. Compared to a long carbon chaincorrosion inhibitor, the short carbon chain corrosion inhibitor is aptto bond to the hydrophobic first region.

In some embodiments, after the surface treatment to the first region isperformed, the material of the first region has a degree ofhydrophilicity similar to a degree of a material of the second region.The polishing slurry can be dispersed on the first region and the secondregion more uniformly, and thus dishing can be mitigated.

FIG. 3 is a flowchart illustrating a chemical mechanical polishing (CMP)method in accordance with various aspects of the present disclosure. Themethod 400 begins with operation 410 in which a substrate is provided,wherein the substrate has a first material and a second material formedthereon, the second material is over a side surface and an upper surfaceof the first material, and a degree of hydrophobicity or hydrophilicityof the first material is different from that of the second material. Themethod 400 continues with operation 420 in which a polishing slurry isprovided on the substrate. The method 400 proceeds with operation 430 inwhich a CMP operation is performed to remove the second material overthe upper surface of the first material to expose the upper surface ofthe first material and an upper surface of the second material, whereinthe polishing slurry and the upper surface of the second material have afirst contact angle, and the polishing slurry and the upper surface ofthe first material have a second contact angle. The method 400 proceedswith operation 440 in which the upper surface of the second material ismodified to make a contact angle difference between the first contactangle and the second contact angle equal to or less than 30 degrees. Themethod 400 proceeds with operation 450 in which the CMP operation iscontinued to perform on the first material and the second material withthe polishing slurry.

The method 400 is merely an example, and is not intended to limit thepresent disclosure beyond what is explicitly recited in the claims.Additional operations can be provided before, during, and after themethod 400, and some operations described can be replaced, eliminated,or moved around for additional embodiments of the method.

FIG. 4 , FIG. 5 and FIG. 6 are schematic diagrams of a planarizationmethod in accordance with various aspects of some embodiments of thepresent disclosure. As shown in FIG. 4 , a semiconductor structure 30including a substrate 300 is provided. In some embodiments, a surface300 a of the substrate 300 includes a first region 310 and a secondregion 311. The first region 310 and the second region 311 includedifferent materials. In some embodiments, the first region 310 is ahydrophobic region having a hydrophobic surface 310 a, and the secondregion 311 is a hydrophilic region having a hydrophilic surface 311 a.In some embodiments, the semiconductor structure 30 may include adielectric layer having via holes, and a metal layer over the dielectriclayer and filled in the via holes. By way of example, the first region310 may be formed from metal material such as cobalt, copper, tungstenor other suitable metal materials, while the second region 311 may beformed from dielectric material such as silicon oxide, silicon nitrideor other suitable dielectric materials. In some other embodiments, thefirst region 310 may be formed from semiconductor material such aspolycrystalline silicon, while the second region 311 may be formed fromdielectric material such as silicon oxide, silicon nitride or othersuitable dielectric materials. In some other embodiments, the firstregion 310 may be formed from dielectric material such as siliconnitride, while the second region 311 may be formed from dielectricmaterial such as silicon oxide. In some embodiments, a polishing slurry302 is dispensed on the surface 310 a of the first region 310 and thesurface 311 a of the second region 311. In some embodiments, thepolishing slurry 302 includes a plurality of polishing abrasives 308. Insome embodiments, the plurality of polishing abrasives 308 is made ofcorundum, tungsten carbide, silicon carbide (carborundum), titaniumcarbide, boron, boron nitride, rhenium diboride, stishovite, titaniumdiboride, diamond, carbonado, or the like.

As the surface 310 a of the first region 310 is hydrophobic, thepolishing slurry 302 shows a bead shaped drop having a smaller contactarea with the surface 310 a. On the other hand, as the surface 311 a ofthe second region 311 is hydrophilic, the polishing slurry 302 is spreadout on the surface 311 a of the second region 311, and has a largercontact area with the surface 311 a. As a result, the polishing slurry302 and the surface 310 a of the first region 310 have a first contactangle 312, the polishing slurry 302 and the surface 311 a of the secondregion 311 have a second contact angle 314, and the first contact angle312 is larger than the second contact angle 314. In some embodiments,the first contact angle 312 is greater than 90 degrees. In someembodiments, the contact angle difference between the first contactangle 312 and the second contact angle 314 is greater than 30 degrees.

As shown in FIG. 5 , a surface treatment is carried out to modify thesurface 310 a of the first region 310 by transforming a material of thefirst region 310 into another material. In some embodiments, the surface310 a of the first region 310 is modified by adding a pH adjuster to thepolishing slurry 302. In some embodiments, the material of the firstregion 310 is transformed to form an oxide compound on the surface 310 aof the first region 310. In some embodiments, the pH adjuster includesmaleic acid, sulfuric acid, nitric acid, potassium hydroxide, amine,sodium hypochlorite, tetramethylammonium hydroxide (TMAH), ammonium, ora combination thereof. In some embodiments, the material of the firstregion 310 is apt to be oxidized in an alkaline environment, such ascobalt or copper. In some embodiments, the material of the first region310 is apt to be oxidized in an acidic environment, such as tungsten.Therefore, the pH value of the polishing slurry 302 may be modified toform the oxide compound based on the material of the first region 310.When the material of the first region 310 is apt to be oxidized in analkaline environment, an alkaline pH adjuster is selected to enhanceformation of metal oxide such as cobalt oxide or copper oxide on thesurface 310 a of the first region 310. When the material of the firstregion 310 is apt to be oxidized in an acidic environment, an acidic pHadjuster is selected to enhance formation of metal oxide such astungsten oxide on the surface 310 a of the first region 310.

As shown in FIG. 5 , the polishing slurry 302 and the oxide compound 320on the surface 310 a of the first region 310 have a third contact angle316 after the surface treatment. In some embodiments, the third contactangle 316 is less than 90 degrees. In some embodiments, the contactangle difference between the second contact angle 314 and the thirdcontact angle 316 is equal to or less than 30 degrees. With thehydrophilic oxide compound 320, the surface 310 a of the first region310 and the second surface 311 a of the second region 311 can havesimilar degree of hydrophilicity. Accordingly, the polishing slurry 302can be dispersed on the oxide compound 320 of the first region 310 andthe surface 311 a of the second region 311 more uniformly after thesurface treatment. As a result, the plurality of polishing abrasives 308can also be dispersed on the oxide compound 320 of the first region 310and the surface 311 a of the second region 311 more uniformly during CMPoperation.

As shown in FIG. 6 , as the substrate 300 is polished with the polishingslurry 302, the oxide compound 320 on the surface 310 a of the firstregion 310 may be polished as well, and the surface 310 a of the firstregion 310 may be exposed. The surface 310 a of the first region 310,however, will keep on being oxidized, and a new layer of oxide compound320 will be formed as the pH adjuster of the polishing slurry 302 ispresented as illustrated in FIG. 5 . Accordingly, the surface 310 a ofthe first region 310 and the second surface 311 a of the second region311 can constantly have similar degree of hydrophilicity, and thereforethe surface 310 a of the first region 310 and the second surface 311 aof the second region 311 can be polished uniformly.

In some embodiments, after the surface of the substrate 300 isplanarized, the pH value of the polishing slurry 302 can be adjusted toinhibit formation of the oxide compound 320 on the surface 310 a of thefirst region 310.

FIG. 7 , FIG. 7A and FIG. 8 are schematic diagrams of a planarizationmethod in accordance with various aspects of some embodiments of thepresent disclosure. As shown in FIG. 7 , the surface 310 a of the firstregion 310 is hydrophobic, and the surface 311 a of the second region311 is hydrophilic.

As shown in FIG. 7A, a surface treatment is carried out to modify thesurface 310 a of the first region 310 by adding a surfactant 330 to thepolishing slurry 302. The surfactant 330 may be configured to preventparticles such as polishing abrasives 308 from being adhered to thesurfaces 310 a and 311 a. In some embodiments, the material of thesurfactant 330 is selected to be bonded to the surface 310 a of thefirst region 310 than to the surface 311 a of the second region 311. Forexample, the surfactant 330, which is being neutral or carries a fewpositive charges, is liable to bond to the surface 310 a of the firstregion 310 than to the surface 311 a of the second region 311 by ionicbond because the hydrophobic first region 310 carries fewer negativecharges than the hydrophilic second region 311. With the surfactant 330bonded to the surface 310 a of the first region 310, the surface 310 aof the first region 310 can be modified to have a degree ofhydrophilicity similar to that of the surface 311 a of the second region311. Accordingly, the polishing slurry 302 and the surface 310 a of thefirst region 310 with the surfactant 330 adhered to have the thirdcontact angle 316. In some embodiments, the third contact angle 316 isless than 90 degrees. In some embodiments, the contact angle differencebetween the second contact angle 314 and the third contact angle 316 isequal to or less than 30 degrees. The surfactant 330 may help to alterthe degree of hydrophilicity of the first region 310, and thereforereduces the contact angle difference between the second contact angle314 and the third contact angle 316.

As shown in FIG. 7A, the surfactant 330 includes a hydrophilic end 330Aand a hydrophobic end 330B. In some embodiments, the hydrophobic end330B is bonded to the surface 310 a of the first region 310 by ionicbond, for example, while the hydrophilic end 330A is in the polishingslurry 302. In some embodiments, the surfactant 330 includes an anionicsurfactant, a cationic surfactant, an amphoteric surfactant, a nonionicsurfactant, or a combination thereof. Examples of the material for thesurfactant 330 may include, but is not limited to, Acetate cationicsurfactant, sulfate cationic surfactant, polyacrylic acid or the like.As the surfactant 330 alters the degree of hydrophilicity of the firstregion 310, the polishing slurry 302 can be dispersed on the surface 310a of the first region 310 and the surface 311 a of the second region 311more uniformly. Accordingly, the plurality of polishing abrasives 308can also be dispersed on the surface 310 a of the first region 310 andthe surface 311 a of the second region 311 more uniformly during CMPoperation.

As shown in FIG. 8 , as the substrate 300 is polished with the polishingslurry 302, the surfactant 330 on the surface 310 a of the first region310 may be polished as well, and the surface 310 a of the first region310 may be exposed. The surfactant 330 of the polishing slurry 302,however, will keep on bonding to the surface 310 a of the first region310 as illustrated in FIG. 7 . Accordingly, the surface 310 a of thefirst region 310 and the second surface 311 a of the second region 311can constantly have similar degree of hydrophilicity, and therefore thesurface 310 a of the first region 310 and the second surface 311 a ofthe second region 311 can be polished uniformly. In some embodiments,after the surface of the substrate 300 is planarized, the surfactant 330of the polishing slurry 302 can be reduced such that the surfactant 330is not bonded to the surface 310 a of the first region 310.

FIG. 9 , FIG. 9A and FIG. 10 are schematic diagrams of a planarizationmethod in accordance with various aspects of some embodiments of thepresent disclosure. As shown in FIG. 9 , the surface 310 a of the firstregion 310 is hydrophobic and the surface 311 a of the second region 311is hydrophilic.

As shown in FIG. 9A, a surface treatment is performed to modify thesurface 310 a of the first region 310 by adding a corrosion inhibitor340 to the polishing slurry 302. The corrosion inhibitor 340 may beconfigured to alleviate corrosion of the material (such as metal) of thefirst region 310 or the second region 311. In some embodiments, thematerial of the corrosion inhibitor 340 is selected to be bonded to thesurface 310 a of the first region 310 than to the surface 311 a of thesecond region 311. For example, the corrosion inhibitor 340, which isbeing neutral or carries a few positive charges, is liable to bond tothe surface 310 a of the first region 310 than to the surface 311 a ofthe second region 311 by ionic bond because the hydrophobic first region310 carries fewer negative charges than the hydrophilic second region311. With the corrosion inhibitor 340 bonded to the surface 310 a of thefirst region 310, the surface 310 a of the first region 310 can bemodified to have a degree of hydrophilicity similar to that of thesurface 311 a of the second region 311. Accordingly, the polishingslurry 302 and the surface 310 a of the first region 310 with thecorrosion inhibitor 340 adhered to have the third contact angle 316. Insome embodiments, the third contact angle 316 is less than 90 degrees.In some embodiments, the contact angle difference between the secondcontact angle 314 and the third contact angle 316 is equal to or lessthan 30 degrees. The corrosion inhibitor 340 may help to alter thedegree of hydrophilicity of the first region 310, and therefore reducesthe contact angle difference between the second contact angle 314 andthe third contact angle 316.

As shown in FIG. 9A, the corrosion inhibitor 340 may include a carbonchain 340A and a functional group 340B. In some embodiments, thefunctional group 340B is bonded to the surface 310 a of the first region310 by ionic bond, hydrogen bond or the like, while the carbon chain340A is in the polishing slurry 302. In some embodiments, the corrosioninhibitor 340 includes a short carbon chain corrosion inhibitor with acarbon number less than 20. Compared to a long carbon chain corrosioninhibitor, the short carbon chain corrosion inhibitor 340 is morehydrophilic. Therefore, the short carbon chain corrosion inhibitor 340bonded to the hydrophobic first region 310 can increase the degree ofhydrophilicity of the surface 310 a of the first region 310. Examples ofthe material for the corrosion inhibitor 340 may include, but is notlimited to, Benzotriazole (BTA), phosphate cationic inhibitor, aminecationic inhibitor, histidine or the like. Accordingly, the polishingslurry 302 can be dispersed on the surface 310 a of the first region 310and the surface 311 a of the second region 311 more uniformly after thesurface 310 a of the first region 310 is modified by the corrosioninhibitor 340. Accordingly, the plurality of polishing abrasives 308 canalso be dispersed on the surface 310 a of the first region 310 and thesurface 311 a of the second region 311 more uniformly during CMPoperation.

As shown in FIG. 10 , as the substrate 300 is polished with thepolishing slurry 302, the corrosion inhibitor 340 on the surface 310 aof the first region 310 may be polished as well, and the surface 310 aof the first region 310 may be exposed. The corrosion inhibitor 340 ofthe polishing slurry 302, however, will keep on bonding to the surface310 a of the first region 310 as illustrated in FIG. 9 . Accordingly,the surface 310 a of the first region 310 and the second surface 311 aof the second region 311 can constantly have similar degree ofhydrophilicity, and therefore the surface 310 a of the first region 310and the second surface 311 a of the second region 311 can be polisheduniformly. In some embodiments, after the surface of the substrate 300is planarized, the corrosion inhibitor 340 of the polishing slurry 302can be reduced such that the corrosion inhibitor 340 is not bonded tothe surface 310 a of the first region 310.

FIG. 11A, FIG. 11B, FIG. 11C and FIG. 11D are schematic cross-sectionalviews illustrating a CMP method in accordance with some embodiments ofthe present disclosure. As shown in FIG. 11A, a semiconductor structure10 is provided. In some embodiments, the semiconductor structure 10includes a substrate 100, a first material 102 and a second material104. The second material 104 is formed over a side surface 102S and anupper surface 102U of the first material 102. The first material 102 andthe second material 104 have different degrees of hydrophobicity orhydrophilicity. In some embodiments, the first material 102 may includea dielectric material such as silicon oxide compound or silicon nitridecompound configured as dielectric layer. In some embodiments, the secondmaterial 104 may include a conductive material such as metal materialconfigured as conductive vias. The second material 104 over the firstmaterial 102 may need to be removed to form a plurality of separatedconductive vias, and the upper surface 102U of the first material 102and the upper surface 104U of the second material 104 may need to beplanarized for successive operations. In some other embodiments, thefirst material 102 may include a dielectric material such as siliconoxide compound configured as a dielectric layer, and the second material104 may include a semiconductor material such as polycrystalline siliconconfigured as poly gate or dummy poly gate. In some other embodiments,the first material 102 may include a dielectric material such as siliconnitride compound configured as a hard mask, and the second material 104may include another dielectric material such as silicon oxide compoundconfigured as a dielectric layer.

A polishing slurry 120 may be dispensed over the semiconductor structure10, and a CMP operation may be performed to remove the second material104 over the first material 102. As shown in FIG. 11A, since the secondmaterial 104 has the same degree of hydrophobicity or hydrophilicity,the abrasives of the polishing slurry 120 may be uniformly distributedover the second material 104.

As shown in FIG. 11B, when the second material 104 over the firstmaterial 102 is polished by the CMP operation, the upper surface 102U ofthe first material 102 and the upper surface 104U of the second material104 will be exposed. Since the the first material 102 and the secondmaterial 104 have different degrees of hydrophobicity or hydrophilicity,the polishing slurry 120 and the upper surface 104U of the secondmaterial 104 have a first contact angle (as shown in FIG. 4 , FIG. 8 orFIG. 10 ), and the polishing slurry 120 and the upper surface 102U ofthe first material 102 have a second contact angle (as shown in FIG. 4 ,FIG. 8 or FIG. 10 ).

As shown in FIG. 11C, the upper surface 104U of the second material 104is modified to make a contact angle difference between the first contactangle and the second contact angle equal to or less than 30 degrees. Theupper surface 104U of the second material 104 may be modified by addingthe pH adjuster, surfactant or corrosion inhibitor as described in theembodiments of FIGS. 4-10 , for example.

As shown in FIG. 11D, the CMP operation is continued to perform on thefirst material 102 and the second material 104 with the polishing slurry120 uniformly dispensed on the upper surface 102U of the first material102 and the upper surface 104U of the second material 104. Accordingly,dishing during the CMP operation may be mitigated.

In some embodiments of the present disclosure, the planarization methoduses a surface treatment to modify the surface of the substrate or itsoverlying layer(s), such that the substrate or the overlying layer(s)may have similar degree of hydrophobicity or hydrophilicity. Withsimilar degree of hydrophobicity or hydrophilicity across differentregions, the polishing slurry can be uniformly dispersed on thesubstrate. Consequently, dishing can be alleviated during theplanarization operation.

In some embodiments of the present disclosure, a planarization method isprovided. The planarization method includes: providing a substrate,wherein the substrate includes a first region and a second region havingdifferent degrees of hydrophobicity or hydrophilicity, the second regioncovering an upper surface of the first region; polishing the substratewith a polishing slurry until the upper surface of the first region isexposed, wherein the polishing exposes an upper surface of the secondregion; and continuing polishing and performing a surface treatment bythe polishing slurry to adjust the degree of hydrophobicity orhydrophilicity of at least one of the first region and the secondregion. The first region includes a metal material including at leastone of cobalt, copper and tungsten, the second region includes adielectric material including at least one of silicon oxide compound andsilicon nitride compound, the polishing slurry and the upper surface ofthe second region have a first contact angle, and the polishing slurryand the upper surface of the first region have a second contact angle.The surface treatment keeps a contact angle difference between the firstcontact angle and the second contact angle being equal to or less than30 degrees during the polishing.

In some embodiments of the present disclosure, a chemical mechanicalpolishing (CMP) method is provided. The CMP method includes: providing asubstrate having a first material including a metal including at leastone of cobalt, copper and tungsten, and a second material including adielectric material including a silicon oxide compound formed thereon,wherein the second material includes a top portion disposed over thefirst material; performing a CMP operation with a polishing slurry toremove the top portion of the second material over the upper surface ofthe first material until the upper surface of the first material and anupper surface of the second material are exposed; and continuing the CMPoperation and performing a surface treatment to transform the metal onthe upper surface of the first material into a metal oxide compoundduring the CMP operation. The polishing slurry and the upper surface ofthe second material have a first contact angle, and the polishing slurryand the upper surface of the first material have a second contact angle.The surface treatment keeps a contact angle difference between the firstcontact angle and the second contact angle being equal to or less than30 degrees during the CMP operation.

In some embodiments of the present disclosure, a chemical mechanicalpolishing (CMP) method is provided. The CMP method includes: providing asubstrate having a dielectric material including silicon oxide compoundor silicon nitride compound and a metal material including cobalt,copper or tungsten formed thereon, wherein the metal material includes atop portion disposed over an upper surface of the dielectric material;performing a CMP operation with a polishing slurry to remove the topportion of the metal material over the upper surface of the dielectricmaterial until the upper surface of the dielectric material and an uppersurface of the metal material are exposed; and performing, during theCMP operation, a surface treatment to adjust a degree of hydrophobicityor hydrophilicity of at least one of the metal material and thedielectric material by the polishing slurry. The polishing slurry andthe upper surface of the dielectric material have a first contact angle,and the polishing slurry and the upper surface of the metal materialhave a second contact angle. The surface treatment causes a contactangle difference between the first contact angle and the second contactangle being equal to or less than 30 degrees during the CMP operation.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingothers and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A planarization method, comprising: providing asubstrate, wherein the substrate includes a first region and a secondregion having different degrees of hydrophobicity or hydrophilicity, thesecond region covering an upper surface of the first region; polishingthe substrate with a polishing slurry until the upper surface of thefirst region is exposed, wherein the polishing exposes an upper surfaceof the second region; and continuing polishing and performing a surfacetreatment by the polishing slurry to adjust the degree of hydrophobicityor hydrophilicity of at least one of the first region and the secondregion, wherein the first region comprises a metal material including atleast one of cobalt, copper and tungsten, the second region comprises adielectric material including at least one of silicon oxide compound andsilicon nitride compound, the polishing slurry and the upper surface ofthe second region have a first contact angle, and the polishing slurryand the upper surface of the first region have a second contact angle,wherein the surface treatment keeps a contact angle difference betweenthe first contact angle and the second contact angle being equal to orless than 30 degrees during the polishing.
 2. The planarization methodof claim 1, wherein the surface treatment comprises transforming amaterial of the first region into another material having a degree ofhydrophobicity or hydrophilicity different from a degree ofhydrophobicity or hydrophilicity of the material of the first region. 3.The planarization method of claim 2, wherein the transforming thematerial of the first region into another material comprises adding a pHadjuster to the polishing slurry.
 4. The planarization method of claim3, wherein the pH adjuster comprises maleic acid, sulfuric acid, nitricacid, potassium hydroxide, amine, sodium hypochlorite,tetramethylammonium hydroxide (TMAH), ammonium, or a combinationthereof.
 5. The planarization method of claim 1, wherein the surfacetreatment comprises adding a surfactant to the polishing slurry, thesurfactant is bonded to the surface of the first region during thepolishing and performing the surface treatment, and the surfactantcomprises a functional group.
 6. The planarization method of claim 5,wherein the surfactant comprises anionic surfactant, cationicsurfactant, amphoteric surfactant, nonionic surfactant, or a combinationthereof.
 7. The planarization method of claim 1, wherein the surfacetreatment comprises adding a corrosion inhibitor to the polishingslurry, the corrosion inhibitor is bonded to the upper surface of thefirst region during the polishing and performing the surface treatment.8. The planarization method of claim 7, wherein the corrosion inhibitorcomprises a short carbon chain corrosion inhibitor with a carbon numberless than
 20. 9. A chemical mechanical polishing (CMP) method,comprising: providing a substrate having a first material comprising ametal including at least one of cobalt, copper and tungsten, and asecond material comprising a dielectric material including a siliconoxide compound formed thereon, wherein the second material includes atop portion disposed over the first material; performing a CMP operationwith a polishing slurry to remove the top portion of the second materialover an upper surface of the first material until the upper surface ofthe first material and an upper surface of the second material areexposed; and continuing the CMP operation and performing a surfacetreatment to transform the metal on the upper surface of the firstmaterial into a metal oxide compound during the CMP operation, whereinthe polishing slurry and the upper surface of the second material have afirst contact angle, and the polishing slurry and the upper surface ofthe first material have a second contact angle, wherein the surfacetreatment keeps a contact angle difference between the first contactangle and the second contact angle being equal to or less than 30degrees during the CMP operation.
 10. The CMP method of claim 9, whereinthe upper surface of the second material is hydrophobic, and the uppersurface of the first material is hydrophilic region.
 11. The CMP methodof claim 9, wherein the transforming of the metal into the metal oxidecompound comprises adding a pH adjuster to the polishing slurry.
 12. TheCMP method of claim 9, wherein the transforming of the metal on theupper surface of the first material comprises adding a surfactant to thepolishing slurry, the surfactant is bonded to the upper surface of thesecond material during the CMP operation such that the contact angledifference between the first contact angle and the second contact angleis reduced.
 13. The CMP method of claim 9, wherein the transforming ofthe metal on the upper surface of the first material comprises adding acorrosion inhibitor to the polishing slurry, the corrosion inhibitor isbonded to the upper surface of the second material during the CMPoperation such that the contact angle difference between the firstcontact angle and the second contact angle is reduced.
 14. A chemicalmechanical polishing (CMP) method, comprising: providing a substratehaving a dielectric material comprising silicon oxide compound orsilicon nitride compound and a metal material comprising cobalt, copperor tungsten formed thereon, wherein the metal material includes a topportion disposed over an upper surface of the dielectric material;performing a CMP operation with a polishing slurry to remove the topportion of the metal material over the upper surface of the dielectricmaterial until the upper surface of the dielectric material and an uppersurface of the metal material are exposed; and performing, during theCMP operation, a surface treatment to adjust a degree of hydrophobicityor hydrophilicity of at least one of the metal material and thedielectric material by the polishing slurry, wherein the polishingslurry and the upper surface of the dielectric material have a firstcontact angle, and the polishing slurry and the upper surface of themetal material have a second contact angle, wherein the surfacetreatment causes a contact angle difference between the first contactangle and the second contact angle being equal to or less than 30degrees during the CMP operation.
 15. The CMP method of claim 14,wherein the surface treatment further comprises transforming the metalmaterial into a metal oxide compound by adding a pH adjuster to modify apH value of the polishing slurry, and the dielectric material comprisesa semiconductor oxide compound during the CMP operation.
 16. The CMPmethod of claim 15, wherein the pH adjuster comprises maleic acid,sulfuric acid, nitric acid, potassium hydroxide, amine, sodiumhypochlorite, tetramethylammonium hydroxide (TMAH), ammonium, or acombination thereof.
 17. The CMP method of claim 14, wherein the surfacetreatment further comprises adding a surfactant to the polishing slurry,the surfactant is bonded to the upper surface of the metal materialduring the CMP operation, and the surfactant comprises a functionalgroup.
 18. The CMP method of claim 17, wherein the surfactant comprisesanionic surfactant, cationic surfactant, amphoteric surfactant, nonionicsurfactant, or a combination thereof.
 19. The CMP method of claim 14,wherein the surface treatment further comprises adding a corrosioninhibitor to the polishing slurry, wherein the corrosion inhibitorcomprises a short carbon chain corrosion inhibitor with a carbon numberless than about
 20. 20. The CMP method of claim 19, wherein thepolishing slurry further comprises polishing abrasives, chemicalreagents and other additives.